Flash smelting of iron with finely divided coal in a vertical shaft furnace is described in the Roberts U.S. Pat. No. 3,822,125, July 2, 1974. In this patent, which is directed to iron smelting only, there is a large recirculation of hydrogen, for example from 12 to 22 or more moles per mole of iron ore, figured as Fe.sub.2 O.sub.3. Part of the hydrogen is burned with oxygen to produce steam, and the off gases contain carbon monoxide, steam and excess hydrogen. After cooling the off gases, they are subjected to the water gas shift process and the carbon monoxide is transformed into carbon dioxide and hydrogen, followed by separation of the gases. When considering a flash smelting process of iron ore alone, the Roberts process is very economical as it can use coal which does not need to be coking coal and which may even contain substantial amounts of sulfur, which reacts with the limestone present in the smelting and appears as calcium sulfide in the slag.